Update node version & travis script

Author: wanseob

Diff for: .travis.yml

@@ -1,7 +1,12 @@
 language: node_js
 node_js:
-  - '0.11'
-  - '0.10'
+  - "stable"
+
+install:
+  - npm install
+
+script:
+  - npm run test
 
 after_success:
   - CURRENT_VERSION=$(node -p "require('./package.json').version")